The present invention relates to a slider for a slide fastener, and in particular to an improved automatic lock slider for a slide fastener.
Referring to FIG. 1, the exploded perspective view of the structure of a conventional automatic lock slider for a slide fastener is shown. FIG. 2 is a diagram showing the conventional automatic lock slider for a slide fastener mounted on the stringers 50, 50' of a slide fastener. The slider 20 includes a slider body 22, a lug 24, a pull 30 and an elastic strip 28. The slider body 22 is composed of an upper side wall 221, a lower side wall 222, and a wedge-shaped diamond (not shown) which joins the upper side wall 221 to the lower side wall 222 and forms notches 223 for receiving the stringers 50, 50' (FIG. 2). The upper side wall 221 has a flared end 221a and a contracted end 221b. A lug 24 is integrally formed with the upper side wall 221 of the slider body 22 with its one end connected to the flared end 221a and the other end connected to the contracted end 221b, for connection with a pull 26. The pull 26 is provided with a wire loop 32 which is attached to the pull body 30 and forms an aperture 33 in which lug 24 and elastic strip 28 are disposed. The elastic strip 28, which is made of, for example metal, is disposed between the lug 24 and the upper side wall 221 of the slide body 22 with its fixed end being inserted into the hole 25 formed in one end of the lug 24 and its free end being positioned within a notch 241 formed in the connection at contracted end 221b. A downward protrusion 29 is formed at the free end of the elastic strip 28. Thus, when the pull 26 is released, the downward protrusion 29 will be inserted into the gap between the interlocked teeth due to the resilient property of the elastic strip 28, and thus the downward protrusion 29 will provide positive locking action on the stringers 50, 50' to prevent the slider 20 from moving. When the pull 26 is pulled, the elastic strip 28 is rotated around its fixing end, making its free end detach from the gap between the interlocked teeth and thus allowing the slider 20 move to open or close the slide fastener.
However, as shown in FIG. 1, for a conventional slider 20 of a slide fastener, when the elastic strip 28 is to be disposed between lug 24 and the upper slide wall 221, as the strip 28 is elastic and is in curved shape, and is to be passed over one end of the wire loop 32, sufficient space is needed for this installation. That is, the distance d should be high enough for the insertion of the elastic strip 28. However, when a sufficient space is provided, as shown in FIG. 2, the strip 28 will have a large space for deformation when it is pulled by the pull 26, rendering the quick elastic fatigue of the elastic strip 28. To avoid the above drawback, the height of the lug 24 should be reduced to prevent the elastic strip 28 from being excessively deformed when it is pulled. With the height of the lug 24 being reduced, the ring-shaped end of the pull 26, that is connected to the lug 24, can not but be made thinner to save the space. This is the reason why a wire loop 32 made of metal is usually used for this purpose. Another reason for using a metal wire loop 32 is to provide sufficient strength to the pull 26 to avoid its breakage. However, as the ring-shaped end is made with a metal wire loop which is usually of different material from that of the pull, the manufacturing cost is thus increased and such a combination can not be formed by the plastics injection molding technique.